1. International public opinion
2. U.S. public opinion
4. The Convention Against Torture
Here are some data on the acceptability, according to public opinion, of the use of torture. (A more descriptive post on torture is here).
In an October 2007 Rasmussen poll, 27 percent of Americans surveyed said the United States should torture prisoners captured in the fight against terrorism, while 53 percent said it should not. In [a 2012] YouGov poll, 41 percent said they would be willing to use torture — a gain of 14 points — while 34 percent would not, a decline of 19 points. (source)
Respondents in 2012 are more pro-waterboarding, pro-threatening prisoners with dogs, pro-religious humiliation, and pro-forcing-prisoners-to-remain-naked-and-chained-in-uncomfortable-positions-in-cold-rooms. In 2005, 18 percent said they believed the naked chaining approach was OK, while 79 percent thought it was wrong. In 2012, 30 percent of Americans thought this technique was right, an increase of 12 points, while just 51 percent thought it was wrong, a drop of 28 points. In 2005, only 16 percent approved of waterboarding suspected terrorists, while an overwhelming majority (82 percent) thought it was wrong to strap people on boards and force their heads underwater to simulate drowning. Now, 25 percent of Americans believe in waterboarding terrorists, and only 55 percent think it’s wrong. The only specific interrogation technique that is less popular now than in 2005, strangely enough, is prolonged sleep deprivation. (source)
Here are the countries that have ratified the CAT:
There’s an optional protocol to the CAP, which provides for the establishment of “a system of regular visits undertaken by independent international and national bodies to places where people are deprived of their liberty, in order to prevent torture and other cruel, inhuman or degrading treatment or punishment”. The following countries have signed or ratified this protocol:
If it’s generally true that countries sign treaties because they believe in them, then we can claim that the first map shows the extent of the universal acceptance of the immorality of torture, not of course the extent of actual torture. It corroborates what I wrote before on the legal and moral universality of human rights. For a more pessimistic view of legal universality, go here.
Here are some data on the actual effectiveness of CAT in reducing torture:
The x-axis shows the five years before and after a country ratified the CAT. Year 0 is the year that the country ratified the CAT. For example, year 0 for the United States was 1994, while year 0 for Nicaragua was 2005. The line shows the average torture score for countries during the five years leading up to ratification and the five years following ratification (where 0 refers to frequent torture and 2 refers to no torture). If the average country had reduced torture during this period, then the line would have sloped up. The data source is Cingranelli-Richards. (source)